﻿#region License
// Copyright (c) 2007 James Newton-King
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Reflection;
using System.Runtime.Serialization;
using Newtonsoft.Json.Utilities;
#if NET20
using Newtonsoft.Json.Utilities.LinqBridge;
#else
using System.Linq;

#endif

namespace Newtonsoft.Json.Converters
{
    /// <summary>
    /// Converts an <see cref="Enum"/> to and from its name string value.
    /// </summary>
    public class StringEnumConverter : JsonConverter
    {
        private readonly Dictionary<Type, BidirectionalDictionary<string, string>> _enumMemberNamesPerType = new Dictionary<Type, BidirectionalDictionary<string, string>>();

        /// <summary>
        /// Gets or sets a value indicating whether the written enum text should be camel case.
        /// </summary>
        /// <value><c>true</c> if the written enum text will be camel case; otherwise, <c>false</c>.</value>
        public bool CamelCaseText { get; set; }

        /// <summary>
        /// Gets or sets a value indicating whether integer values are allowed.
        /// </summary>
        /// <value><c>true</c> if integers are allowed; otherwise, <c>false</c>.</value>
        public bool AllowIntegerValues { get; set; }

        /// <summary>
        /// Initializes a new instance of the <see cref="StringEnumConverter"/> class.
        /// </summary>
        public StringEnumConverter()
        {
            AllowIntegerValues = true;
        }

        /// <summary>
        /// Writes the JSON representation of the object.
        /// </summary>
        /// <param name="writer">The <see cref="JsonWriter"/> to write to.</param>
        /// <param name="value">The value.</param>
        /// <param name="serializer">The calling serializer.</param>
        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            if (value == null)
            {
                writer.WriteNull();
                return;
            }

            Enum e = (Enum)value;

            string enumName = e.ToString("G");

            if (char.IsNumber(enumName[0]) || enumName[0] == '-')
            {
                // enum value has no name so write number
                writer.WriteValue(value);
            }
            else
            {
                BidirectionalDictionary<string, string> map = GetEnumNameMap(e.GetType());

                string[] names = enumName.Split(',');
                for (int i = 0; i < names.Length; i++)
                {
                    string name = names[i].Trim();

                    string resolvedEnumName;
                    map.TryGetByFirst(name, out resolvedEnumName);
                    resolvedEnumName = resolvedEnumName ?? name;

                    if (CamelCaseText)
                        resolvedEnumName = StringUtils.ToCamelCase(resolvedEnumName);

                    names[i] = resolvedEnumName;
                }

                string finalName = string.Join(", ", names);

                writer.WriteValue(finalName);
            }
        }

        /// <summary>
        /// Reads the JSON representation of the object.
        /// </summary>
        /// <param name="reader">The <see cref="JsonReader"/> to read from.</param>
        /// <param name="objectType">Type of the object.</param>
        /// <param name="existingValue">The existing value of object being read.</param>
        /// <param name="serializer">The calling serializer.</param>
        /// <returns>The object value.</returns>
        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            bool isNullable = ReflectionUtils.IsNullableType(objectType);
            Type t = isNullable ? Nullable.GetUnderlyingType(objectType) : objectType;

            if (reader.TokenType == JsonToken.Null)
            {
                if (!ReflectionUtils.IsNullableType(objectType))
                    throw JsonSerializationException.Create(reader, "Cannot convert null value to {0}.".FormatWith(CultureInfo.InvariantCulture, objectType));

                return null;
            }

            try
            {
                if (reader.TokenType == JsonToken.String)
                {
                    string enumText = reader.Value.ToString();
                    if (enumText == string.Empty && isNullable)
                        return null;

                    string finalEnumText;

                    BidirectionalDictionary<string, string> map = GetEnumNameMap(t);
                    if (enumText.IndexOf(',') != -1)
                    {
                        string[] names = enumText.Split(',');
                        for (int i = 0; i < names.Length; i++)
                        {
                            string name = names[i].Trim();

                            names[i] = ResolvedEnumName(map, name);
                        }

                        finalEnumText = string.Join(", ", names);
                    }
                    else
                    {
                        finalEnumText = ResolvedEnumName(map, enumText);
                    }

                    return Enum.Parse(t, finalEnumText, true);
                }

                if (reader.TokenType == JsonToken.Integer)
                {
                    if (!AllowIntegerValues)
                        throw JsonSerializationException.Create(reader, "Integer value {0} is not allowed.".FormatWith(CultureInfo.InvariantCulture, reader.Value));

                    return ConvertUtils.ConvertOrCast(reader.Value, CultureInfo.InvariantCulture, t);
                }
            }
            catch (Exception ex)
            {
                throw JsonSerializationException.Create(reader, "Error converting value {0} to type '{1}'.".FormatWith(CultureInfo.InvariantCulture, MiscellaneousUtils.FormatValueForPrint(reader.Value), objectType), ex);
            }

            // we don't actually expect to get here.
            throw JsonSerializationException.Create(reader, "Unexpected token {0} when parsing enum.".FormatWith(CultureInfo.InvariantCulture, reader.TokenType));
        }

        private static string ResolvedEnumName(BidirectionalDictionary<string, string> map, string enumText)
        {
            string resolvedEnumName;
            map.TryGetBySecond(enumText, out resolvedEnumName);
            resolvedEnumName = resolvedEnumName ?? enumText;
            return resolvedEnumName;
        }

        private BidirectionalDictionary<string, string> GetEnumNameMap(Type t)
        {
            BidirectionalDictionary<string, string> map;

            if (!_enumMemberNamesPerType.TryGetValue(t, out map))
            {
                lock (_enumMemberNamesPerType)
                {
                    if (_enumMemberNamesPerType.TryGetValue(t, out map))
                        return map;

                    map = new BidirectionalDictionary<string, string>(
                        StringComparer.OrdinalIgnoreCase,
                        StringComparer.OrdinalIgnoreCase);

                    foreach (FieldInfo f in t.GetFields())
                    {
                        string n1 = f.Name;
                        string n2;

#if !NET20
                        n2 = f.GetCustomAttributes(typeof(EnumMemberAttribute), true)
                            .Cast<EnumMemberAttribute>()
                            .Select(a => a.Value)
                            .SingleOrDefault() ?? f.Name;
#else
                        n2 = f.Name;
#endif

                        string s;
                        if (map.TryGetBySecond(n2, out s))
                        {
                            throw new InvalidOperationException("Enum name '{0}' already exists on enum '{1}'."
                                .FormatWith(CultureInfo.InvariantCulture, n2, t.Name));
                        }

                        map.Set(n1, n2);
                    }

                    _enumMemberNamesPerType[t] = map;
                }
            }

            return map;
        }

        /// <summary>
        /// Determines whether this instance can convert the specified object type.
        /// </summary>
        /// <param name="objectType">Type of the object.</param>
        /// <returns>
        /// <c>true</c> if this instance can convert the specified object type; otherwise, <c>false</c>.
        /// </returns>
        public override bool CanConvert(Type objectType)
        {
            Type t = (ReflectionUtils.IsNullableType(objectType))
                ? Nullable.GetUnderlyingType(objectType)
                : objectType;

            return t.IsEnum();
        }
    }
}